The venous system of the legs uses pumps to help return blood to the heart. These pumps are formed from the combined action of various muscle groups and bicuspid one-way valves within the venous vasculature. Venous valves create one way flow to prevent blood from flowing away from the heart and also serve to reduce hydrostatic pressure in the lower legs. When valves fail, blood can pool in the lower legs resulting in swelling and ulcers of the leg. The absence of functioning venous valves can lead to chronic venous insufficiency. Venous insufficiency is a condition in which the veins fail to return blood efficiently to the heart. This condition usually involves one or more of the deep veins. Symptoms include swelling of the legs and pain in the extremities such as a dull aching, heaviness, or cramping.
Techniques for both repairing and replacing the valves exist, but are tedious and require invasive surgical procedures. Direct and indirect valvuoplasty procedures are used to repair damaged valves. Transposition and transplantation are used to replace an incompetent valve. Transposition involves moving a vein with an incompetent valve to a site with a competent valve. Transplantation replaces an incompetent valve with a harvested valve from another venous site. Valves can be transplanted into the venous system, but current devices are not successful enough to see widespread usage.